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mmap
A system call that makes a file or a block of memory appear directly in a program's address space.
Instead of reading a file with explicit read calls, mmap maps it so the file's bytes act like an ordinary array in memory — the operating system loads pages on demand as you touch them. It's also used to grab fresh anonymous memory (backed by nothing on disk) for a program to use. This underpins efficient file access and much of how memory allocators get their raw space.
See also
- mprotectA system call that changes what a program is allowed to do with a region of its memory — read, write, or execute.
- pagingThe virtual-memory scheme that splits memory into fixed-size chunks and maps them flexibly.
- page faultThe interrupt that fires when a program touches memory that isn't currently mapped in.